Broadcast systems are used for transmitting signals, such as digital or analogue television signals, from a broadcast centre to a user, via a medium such as a satellite, cable or terrestrial broadcast link. Receiver/decoders at the user end are used for receiving and/or decoding the signals, typically for input to a television set. In the case of digital transmission, digital channels are encoded into a digital data stream at the transmitter end, and are decoded at the receiver end using a receiver/decoder, which may typically be either in a digital set-top box (DSTB) or in an integrated digital television. In the case of analogue transmission, a receiver/decoder may be provided at the user to convert the transmitted signals into a format for input to a television set.
In known broadcast systems, text messages may be sent along with a transmitted signal. A suitably equipped receiver/decoder extracts the text message from the transmitted signal for display on a television screen. Such messages are accessible by all users with suitably equipped receiver/decoders.
Known system for sending text messages tend to be inflexible.